/*
 * sha1.c - Implementation of SHA1 hash function.
 *
 * Original author: Steve Reid <steve@edmweb.com> 100% Public Domain
 * See <http://www.mirrors.wiretapped.net/security/cryptography/hashes/sha1/sha1.c>
 *
 * Modify the source code with Unix C style by Vincent Wei
 *  - Nov. 2020
 *
 * Copyright (C) 2020, 2021 FMSoft <https://www.fmsoft.cn>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
Test Vectors (from FIPS PUB 180-1)
"abc"
  A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D
"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
  84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1
A million repetitions of "a"
  34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F
*/

#include <config.h>

#include <stdint.h>
#include <string.h>

#include "private/utils.h"

/* #define SHA1HANDSOFF * Copies data before messing with it. */

static void sha1_transform (uint32_t state[5], const uint8_t *buffer);

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* blk0() and blk() perform the initial expand. */
/* I got the idea of expanding during the round function from SSLeay */
#if CPU(LITTLE_ENDIAN)
#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#else
#define blk0(i) block->l[i]
#endif
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

/* Hash a single 512-bit block. This is the core of the algorithm. */
static void
sha1_transform(uint32_t state[5], const uint8_t *buffer)
{
    uint32_t a, b, c, d, e;
    typedef union
    {
        uint8_t c[64];
        uint32_t l[16];
    } CHAR64LONG16;
    CHAR64LONG16 *block;
#ifdef SHA1HANDSOFF
    static uint8_t workspace[64];
    block = (CHAR64LONG16 *) workspace;
    memcpy (block, buffer, 64);
#else
    block = (CHAR64LONG16 *) (void *) buffer;
#endif
    /* Copy context->state[] to working vars */
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    /* 4 rounds of 20 operations each. Loop unrolled. */
    R0 (a, b, c, d, e, 0);
    R0 (e, a, b, c, d, 1);
    R0 (d, e, a, b, c, 2);
    R0 (c, d, e, a, b, 3);
    R0 (b, c, d, e, a, 4);
    R0 (a, b, c, d, e, 5);
    R0 (e, a, b, c, d, 6);
    R0 (d, e, a, b, c, 7);
    R0 (c, d, e, a, b, 8);
    R0 (b, c, d, e, a, 9);
    R0 (a, b, c, d, e, 10);
    R0 (e, a, b, c, d, 11);
    R0 (d, e, a, b, c, 12);
    R0 (c, d, e, a, b, 13);
    R0 (b, c, d, e, a, 14);
    R0 (a, b, c, d, e, 15);
    R1 (e, a, b, c, d, 16);
    R1 (d, e, a, b, c, 17);
    R1 (c, d, e, a, b, 18);
    R1 (b, c, d, e, a, 19);
    R2 (a, b, c, d, e, 20);
    R2 (e, a, b, c, d, 21);
    R2 (d, e, a, b, c, 22);
    R2 (c, d, e, a, b, 23);
    R2 (b, c, d, e, a, 24);
    R2 (a, b, c, d, e, 25);
    R2 (e, a, b, c, d, 26);
    R2 (d, e, a, b, c, 27);
    R2 (c, d, e, a, b, 28);
    R2 (b, c, d, e, a, 29);
    R2 (a, b, c, d, e, 30);
    R2 (e, a, b, c, d, 31);
    R2 (d, e, a, b, c, 32);
    R2 (c, d, e, a, b, 33);
    R2 (b, c, d, e, a, 34);
    R2 (a, b, c, d, e, 35);
    R2 (e, a, b, c, d, 36);
    R2 (d, e, a, b, c, 37);
    R2 (c, d, e, a, b, 38);
    R2 (b, c, d, e, a, 39);
    R3 (a, b, c, d, e, 40);
    R3 (e, a, b, c, d, 41);
    R3 (d, e, a, b, c, 42);
    R3 (c, d, e, a, b, 43);
    R3 (b, c, d, e, a, 44);
    R3 (a, b, c, d, e, 45);
    R3 (e, a, b, c, d, 46);
    R3 (d, e, a, b, c, 47);
    R3 (c, d, e, a, b, 48);
    R3 (b, c, d, e, a, 49);
    R3 (a, b, c, d, e, 50);
    R3 (e, a, b, c, d, 51);
    R3 (d, e, a, b, c, 52);
    R3 (c, d, e, a, b, 53);
    R3 (b, c, d, e, a, 54);
    R3 (a, b, c, d, e, 55);
    R3 (e, a, b, c, d, 56);
    R3 (d, e, a, b, c, 57);
    R3 (c, d, e, a, b, 58);
    R3 (b, c, d, e, a, 59);
    R4 (a, b, c, d, e, 60);
    R4 (e, a, b, c, d, 61);
    R4 (d, e, a, b, c, 62);
    R4 (c, d, e, a, b, 63);
    R4 (b, c, d, e, a, 64);
    R4 (a, b, c, d, e, 65);
    R4 (e, a, b, c, d, 66);
    R4 (d, e, a, b, c, 67);
    R4 (c, d, e, a, b, 68);
    R4 (b, c, d, e, a, 69);
    R4 (a, b, c, d, e, 70);
    R4 (e, a, b, c, d, 71);
    R4 (d, e, a, b, c, 72);
    R4 (c, d, e, a, b, 73);
    R4 (b, c, d, e, a, 74);
    R4 (a, b, c, d, e, 75);
    R4 (e, a, b, c, d, 76);
    R4 (d, e, a, b, c, 77);
    R4 (c, d, e, a, b, 78);
    R4 (b, c, d, e, a, 79);
    /* Add the working vars back into context.state[] */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    /* Wipe variables */
    a = b = c = d = e = 0;
}

/* Initialize new context */
void
pcutils_sha1_begin(pcutils_sha1_ctxt *context)
{
    /* SHA1 initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */
void
pcutils_sha1_hash(pcutils_sha1_ctxt *context, const void *data, size_t len)
{
    size_t i, j;
    const uint8_t *bytes = data;

    j = (context->count[0] >> 3) & 63;
    if ((context->count[0] += len << 3) < (len << 3))
        context->count[1]++;
    context->count[1] += (len >> 29);
    if ((j + len) > 63) {
        memcpy (&context->buffer[j], bytes, (i = 64 - j));
        sha1_transform (context->state, context->buffer);
        for (; i + 63 < len; i += 64) {
            sha1_transform (context->state, &bytes[i]);
        }
        j = 0;
    } else
        i = 0;
    memcpy (&context->buffer[j], &bytes[i], len - i);
}

/* Add padding and return the message digest. */
void
pcutils_sha1_end(pcutils_sha1_ctxt *context, uint8_t* digest)
{
    uint32_t i, j;
    uint8_t finalcount[8];

    for (i = 0; i < 8; i++) {
        finalcount[i] = (uint8_t) ((context->count[(i >= 4 ? 0 : 1)]
                    >> ((3 - (i & 3)) * 8)) & 255); /* Endian independent */
    }
    pcutils_sha1_hash (context, (uint8_t *) "\200", 1);
    while ((context->count[0] & 504) != 448) {
        pcutils_sha1_hash (context, (uint8_t *) "\0", 1);
    }
    pcutils_sha1_hash (context, finalcount, 8);  /* Should cause a sha1_transform() */
    for (i = 0; i < 20; i++) {
        digest[i] = (uint8_t)
            ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255);
    }
    /* Wipe variables */
    i = j = 0;
    memset (context->buffer, 0, 64);
    memset (context->state, 0, 20);
    memset (context->count, 0, 8);
    memset (&finalcount, 0, 8);
#ifdef SHA1HANDSOFF     /* make sha1_transform overwrite it's own static vars */
    sha1_transform (context->state, context->buffer);
#endif
}

